The proximity sensor problem appears to be far bigger of a deal than the antenna. Apple Support forums have more posts about the sensor than any other issue with iPhone 4. In fact, they had to close the thread on Apple.com due to too many posts---
Of all the people I know with iPhone 4, none have an antenna issue. But all have issues with the prox sensor.
Of all the people I know with iPhone 4, none have an antenna issue. But all have issues with the prox sensor.